This invention generally relates to water jet apparatus which are mounted to the hull of a boat or other watercraft. In particular, the invention relates to mechanisms for cleaning out an inlet grate of a water jet apparatus which has become clogged with weeds or other debris.
It is known to propel a boat or other watercraft using a water jet apparatus mounted to the hull, with the powerhead being placed inside (inboard) the hull. The drive shaft of the water jet apparatus is coupled to the output shaft of the inboard motor. The impeller is mounted on the drive shaft and housed in a jet propulsion duct.
To facilitate use of water jet-propelled boats in shallow water, it is known to mount the water jet apparatus at an elevation such that the apparatus does not project below the bottom of the boat hull. In one type of design, part of the duct of the water jet apparatus is installed inside the hull while the remaining part penetrates the transom and extends beyond the rear of the hull. An inlet housing of the duct has a horizontal opening and an inlet ramp for guiding water into the housing where the impeller resides. The horizontal opening of the inlet housing is mounted in a hole in the bottom or near the bottom of the hull. A midportion of the duct penetrates a hole in the transom. A water jet stream is discharged out a steering nozzle pivotably mounted to the distal end of the duct.
When operating a water jet-propelled boat in shallow water, it is possible to ingest seaweed and other debris into the duct when water is being drawn into the water jet inlet. To prevent seaweed and other debris from entering the water jet duct and possibly ensnarling or damaging the rotating impeller, a grate or screen is typically placed across the inlet opening. During continuous use of a water jet-propelled watercraft in shallow, weed-infested water, floating weeds can accumulate on and become entangled with the inlet grate to such a degree that the inlet grate becomes clogged. In particular, in the case where the inlet grate comprises an array of mutually parallel tines, the suction created by the impeller causes weeds and other debris to wrap around the tines of the grate and slide rearwardly along the tines. The buildup of weeds, if allowed to continue unabated, can ultimately form a dense mass that reduces the intake of water through the inlet opening and into the water jet. Reduced water flow can cause the jet pump to stall and the boat to stop moving.
The result is that the boat operator must unclog the inlet opening by removing the dense mass of entangled weeds from the tines of the inlet grate. However, removing entangled weeds from the inlet grate can be very difficult. This task can also be unpleasant if a person has to enter the water and submerge under the boat to remove the weeds from the grate. Moreover, even if the entangled weeds are successfully removed, when boat operation is resumed and the boat operator attempts to leave the weeded area, the inlet grate may become plugged after only a short distance, repeating the same clean-out problem.
One method which has been tried to eliminate this problem uses a cantilevered grate that is attached to the top of the inlet housing through a pivot pin. When the grate becomes clogged with weeds, a lever is activated inside the boat that allows the grate to rotate down away from the inlet. The operator then drives the boat forward and the weeds are supposed to slide off the ends of the inlet grate tines. The inlet grate is then rotated back into place.
Another attempt at a solution to the problem of clogged inlet grates was disclosed in U.S. Pat. No. 5,577,941. In that disclosure, the inlet grate comprises a plurality of cantilever tines which extend rearwardly across the water intake and have suspended aft end tips spaced from the aft end of the water intake. This spacing enables rearward sliding of weeds and other debris along and then off of the cantilever tines without clogging. U.S. Pat. No. 5,577,941 characterizes this anti-clogging feature as being xe2x80x9cautomaticxe2x80x9d, with no additional mechanism being needed for unclogging.
U.S. Pat. No. 5,876,258 purports to be an improvement over the teaching of U.S. Pat. No. 5,577,941. In particular, U.S. Pat. No. 5,876,258 states that the inlet grate of U.S. Pat. No. 5,577,941 is problematic because the size of the gap between the end tips of the tines and the aft end of the weed grate plate limits the size and amount of weeds that can pass through the gap and through the water jet. Thus, large clumps of weeds which have a thickness greater than the gap between the tines and the aft end of the inlet grate can cause clogging. Instead, U.S. Pat. No. 5,876,258 proposes an inlet grate comprising a plurality of cantilever tines each joined to a pivot rod. The cantilever tines extend across the inlet opening to prevent debris from entering the water jet. A spring member is mounted between the cantilever tines and a mounting frame such that the spring member provides an outward rotational bias force against the rotatable cantilever tines. During operation of the watercraft, if a mass of weeds becomes clogged in the cantilever tines, the upward and inward suction force of the water jet causes the cantilever tines to rotate upward against the opposing rotational bias force of the spring member. This self-activating mechanism allows the weeds to slide off of the ends of the cantilever tines and be ingested by the water jet. This has the disadvantage that large volumes of weeds will plug up the water jet at the impeller, making clean-out even more difficult than with a fixed-grate system. Also, when the inlet grate is open, hard debris, such as oysters, stones and sticks, can enter the water jet, causing damage to the impeller.
Another grate clean-out device was disclosed in U.S. Pat. No. 6,083,063. This device comprises a cantilevered inlet grate which is pivotably mounted to the top of an inlet housing. The rotation of a lever inside the boat causes the wiper bar to wipe across the top of the tines, which in turn causes the grate to rotate down while causing the weeds to slide off the ends of the tines.
There is a need for an inlet grate clean-out mechanism which can be reliably actuated by a boat operator when conditions require without ingesting weeds or debris into the water jet and which has simplified mechanics.
The present invention is directed to an operator-actuated inlet grate clean-out mechanism which can be actuated as often as required and which has simple mechanics. By linearly displacing an actuator, e.g., by depressing a sliding rod, located in the boat stern, a person can operate a weed wiper which is pivotably coupled to the end of the actuator. The weed wiper is arranged to push weeds off of a pivotable cantilever-tine inlet grate as the wiper travels along the tines toward their tips. As the wiper sweeps along the inlet grate tines, it bears against the inlet grate and causes the grate to swing downward. Because the weeds wrap and ball around the inlet grate, they also slide off easily when pushed or dragged by the sweeping wiper bar even in large quantities. The invention enables fast and easy weed removal, without the necessity of the boat operator entering the water.
One aspect of the invention is directed to a mechanism for cleaning out an inlet grate which extends across an inlet of a duct of a water jet propulsion system. The mechanism comprises an actuator penetrating the duct and a wiper supported by the actuator and disposed across the tines of the inlet grate. The actuator is linearly displaceable. The wiper bears against at least one tine during linear displacement of the actuator from a first position to a second position. The inlet grate pivots from a first angular position to a second angular position as the actuator displaces from the first position to the second position.
Another aspect of the invention is directed to a boat hull comprising: an inlet ramp defining a channel; an inlet grate comprising a plurality of cantilever tines and pivotably mounted to the inlet ramp with its tines extending at least partly across said channel; an actuator which penetrates the inlet ramp and is linearly displaceable; and a wiper supported by the actuator and disposed across the tines. The wiper bears against the tines and causes the inlet grate to pivot, at the same time wiping the tines, as previously described.
In accordance with other aspects of the invention, an inlet grate and a grate clean-out actuator are both coupled to a through-hull housing to form a module or assembly which can be installed in an opening of an inlet ramp formed in the hull. The invention encompasses both a module housing a pivotable inlet grate and a grate clean-out actuator, and a boat hull having such a module installed in an opening in the hull.
In accordance with the preferred embodiment, the actuator penetrates and is supported by a through-hull housing installed in an opening in the hull. The actuator is linearly displaceable relative to the through-hull housing by manipulation of a handle or other operator input device or system. An inlet grate comprising a plurality of cantilever tines is pivotably mounted to and supported by the through-hull housing. A weed wiper is connected to the end of the actuator remote from the end that is actuated by the boat operator. When the actuator is displaced downward, the weed wiper moves downward along a linear path. At the point in the wiper displacement where the wiper bar engages the tines of the inlet grate, the downwardly displacing weed wiper causes the grate to pivot downward. During this action, the wiper slides across the grate and pushes any weeds or other debris entangled on the grate toward the ends of the tines. Because weeds usually wrap and ball around the inlet grate tines, the weeds will slide off easily when pushed or dragged by the sweeping wiper bar.
In accordance with another preferred embodiment, a device is provided which comprises a cantilevered inlet grate mounted on a single-direction pivot with spring return; a weed removal bar; and an actuation rod. The design intent of this grate is to combine the passive weed shedding of a cantilevered grate with an active weed removal system. During normal passive operation, the majority of weeds caught by the grate will be drawn by fluid forces towards the free ends of the tines and slide off. During this phase the grate tines are stationary, forced against the pivot stop by the water flow through the pump inlet. The active mode of operation is used when the inlet grate becomes severely entangled with weeds and pump performance is degraded. The weeds are removed by depressing the actuator rod, which causes the weed removal bar to move in a linear motion and come into contact with the inlet grate, causing it to pivot downward and opening up the gap between the free ends of the tines and the inlet lip. The bar slides down the grate, pushing the entangled weeds off the ends of the tines. Releasing the spring-loaded actuation rod automatically causes all components to retract back into their original positions.